How much of a commodity a consumer buy depends upon which factor/factors?

all of these

Any rational consumer would consider the price of the commodity before buying it. Apart from this, his consumption further depends on the marginal utility he gets when he consume additional units of the same commodity. His desire to further consume the good will highly depend on the fact, that what additional utility does the good offer. Marginal utility of a money that is held constant because it acts as a measuring unit also decides how much of a commodity a consumer buys.